Sidelink connection request based on congestion level

ABSTRACT

A method and apparatus for sidelink connection request based on congestion level for establishing a direct connection between wireless devices is provided. A first wireless device triggers a signaling procedure based on a congestion level of at least one carrier, selects a carrier among the at least one carrier, and transmits a message in the signaling procedure on the selected carrier. Upon receiving the message, a second wireless device may perform carrier reselection.

TECHNICAL FIELD

The present disclosure relates to sidelink connection request based oncongestion level for establishing a direct connection between wirelessdevices.

BACKGROUND

3rd generation partnership project (3GPP) long-term evolution (LTE) is atechnology for enabling high-speed packet communications. Many schemeshave been proposed for the LTE objective including those that aim toreduce user and provider costs, improve service quality, and expand andimprove coverage and system capacity. The 3GPP LTE requires reduced costper bit, increased service availability, flexible use of a frequencyband, a simple structure, an open interface, and adequate powerconsumption of a terminal as an upper-level requirement.

Work has started in international telecommunication union (ITU) and 3GPPto develop requirements and specifications for new radio (NR) systems.3GPP has to identify and develop the technology components needed forsuccessfully standardizing the new RAT timely satisfying both the urgentmarket needs, and the more long-term requirements set forth by the ITUradio communication sector (ITU-R) international mobiletelecommunications (IMT)-2020 process. Further, the NR should be able touse any spectrum band ranging at least up to 100 GHz that may be madeavailable for wireless communications even in a more distant future.

The NR targets a single technical framework addressing all usagescenarios, requirements and deployment scenarios including enhancedmobile broadband (eMBB), massive machine-type-communications (mMTC),ultra-reliable and low latency communications (URLLC), etc. The NR shallbe inherently forward compatible.

Vehicle-to-everything (V2X) communication is the passing of informationfrom a vehicle to any entity that may affect the vehicle, and viceversa. It is a vehicular communication system that incorporates othermore specific types of communication as vehicle-to-infrastructure (V2I),vehicle-to-network (V2N), vehicle-to-vehicle (V2V),vehicle-to-pedestrian (V2P), vehicle-to-device (V2D) and vehicle-to-grid(V2G).

SUMMARY

Until Rel-15, broadcast transmission is supported only for V2Xcommunication. In case of NR V2X, unicast and groupcast transmission mayalso be supported for V2X communication as well as broadcasttransmission. Unicast transmission is expected to be used for highreliability and low latency cases, e.g., extended sensor sharing andremote driving, emergency, etc. Hence, PC5 signaling used forestablishing and/or managing unicast link should also have reliability.

In an aspect, a method for a first wireless device in a wirelesscommunication system is provided. The method includes triggering asignaling procedure based on a congestion level of at least one carrier,selecting a carrier among the at least one carrier, and transmitting amessage in the signaling procedure on the selected carrier.

In another aspect, a method for a second wireless device in a wirelesscommunication system is provided. The method includes monitoring atleast one carrier, receiving, from a first wireless device, a firstmessage on a first carrier among the at least one carrier, performingcarrier reselection from the first carrier to a second carrier among theat least one carrier, and transmitting, to the first wireless device, asecond message as a response to the first message.

In another aspect, an apparatus for implementing the above method isprovided.

The present disclosure can have various advantageous effects.

For example, one wireless device performing sidelink communication canperform fast and reliable connection establishment with another wirelessdevice by selecting multiple carriers of which congestion level is lowenough to provide sidelink grant and reliable signaling to the wirelessdevice with little loss, in particular when what triggers sidelinkconnection or sidelink service are mapped to multiple carriers.

For example, the system can provide fast and reliable sidelinkconnection establishment for a wireless device performing sidelinkcommunication with another wireless device.

Advantageous effects which can be obtained through specific embodimentsof the present disclosure are not limited to the advantageous effectslisted above. For example, there may be a variety of technical effectsthat a person having ordinary skill in the related art can understandand/or derive from the present disclosure. Accordingly, the specificeffects of the present disclosure are not limited to those explicitlydescribed herein, but may include various effects that may be understoodor derived from the technical features of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a communication system to whichimplementations of the present disclosure is applied.

FIG. 2 shows an example of wireless devices to which implementations ofthe present disclosure is applied.

FIG. 3 shows an example of a wireless device to which implementations ofthe present disclosure is applied.

FIG. 4 shows another example of wireless devices to whichimplementations of the present disclosure is applied.

FIG. 5 shows an example of UE to which implementations of the presentdisclosure is applied.

FIGS. 6 and 7 show an example of protocol stacks in a 3GPP basedwireless communication system to which implementations of the presentdisclosure is applied.

FIG. 8 shows a frame structure in a 3GPP based wireless communicationsystem to which implementations of the present disclosure is applied.

FIG. 9 shows a data flow example in the 3GPP NR system to whichimplementations of the present disclosure is applied.

FIGS. 10 and 11 show an example of PC5 protocol stacks to whichimplementations of the present disclosure is applied.

FIG. 12 shows an example of PC5 link setup to which implementations ofthe present disclosure is applied.

FIG. 13 shows an example of security mode control to whichimplementations of the present disclosure is applied.

FIG. 14 shows an example of PC5 link release to which implementations ofthe present disclosure is applied.

FIG. 15 shows an example of a method for a first wireless deviceaccording to implementations of the present disclosure.

FIG. 16 shows an example of a method for a second wireless deviceaccording to implementations of the present disclosure.

FIG. 17 shows an example of for establishing a connection by aninitiating wireless device according to implementations of the presentdisclosure.

FIG. 18 shows an example of for establishing a connection by a targetwireless device according to implementations of the present disclosure.

FIGS. 19 and 20 shows an example of PC5 connection establishment betweentwo UEs according to implementations of the present disclosure.

DETAILED DESCRIPTION

The following techniques, apparatuses, and systems may be applied to avariety of wireless multiple access systems. Examples of the multipleaccess systems include a code division multiple access (CDMA) system, afrequency division multiple access (FDMA) system, a time divisionmultiple access (TDMA) system, an orthogonal frequency division multipleaccess (OFDMA) system, a single carrier frequency division multipleaccess (SC-FDMA) system, and a multicarrier frequency division multipleaccess (MC-FDMA) system. CDMA may be embodied through radio technologysuch as universal terrestrial radio access (UTRA) or CDMA2000. TDMA maybe embodied through radio technology such as global system for mobilecommunications (GSM), general packet radio service (GPRS), or enhanceddata rates for GSM evolution (EDGE). OFDMA may be embodied through radiotechnology such as institute of electrical and electronics engineers(IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or evolved UTRA(E-UTRA). UTRA is a part of a universal mobile telecommunications system(UMTS). 3rd generation partnership project (3GPP) long term evolution(LTE) is a part of evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employsOFDMA in DL and SC-FDMA in UL. LTE-advanced (LTE-A) is an evolvedversion of 3GPP LTE.

For convenience of description, implementations of the presentdisclosure are mainly described in regards to a 3GPP based wirelesscommunication system. However, the technical features of the presentdisclosure are not limited thereto. For example, although the followingdetailed description is given based on a mobile communication systemcorresponding to a 3GPP based wireless communication system, aspects ofthe present disclosure that are not limited to 3GPP based wirelesscommunication system are applicable to other mobile communicationsystems.

For terms and technologies which are not specifically described amongthe terms of and technologies employed in the present disclosure, thewireless communication standard documents published before the presentdisclosure may be referenced.

In the present disclosure, “A or B” may mean “only A”, “only B”, or“both A and B”. In other words, “A or B” in the present disclosure maybe interpreted as “A and/or B”. For example, “A, B or C” in the presentdisclosure may mean “only A”, “only B”, “only C”, or “any combination ofA, B and C”.

In the present disclosure, slash (/) or comma (,) may mean “and/or”. Forexample, “A/B” may mean “A and/orB”. Accordingly, “A/B” may mean “onlyA”, “only B”, or “both A andB”. For example, “A, B, C” may mean “A, B orC”.

In the present disclosure, “at least one of A and B” may mean “only A”,“only B” or “both A and B”. In addition, the expression “at least one ofA or B” or “at least one of A and/or B” in the present disclosure may beinterpreted as same as “at least one of A and B”.

In addition, in the present disclosure, “at least one of A, B and C” maymean “only A”, “only B”, “only C”, or “any combination of A, B and C”.In addition, “at least one of A, B or C” or “at least one of A, B and/orC” may mean “at least one of A, B and C”.

Also, parentheses used in the present disclosure may mean “for example”.In detail, when it is shown as “control information (PDCCH)”, “PDCCH”may be proposed as an example of “control information”. In other words,“control information” in the present disclosure is not limited to“PDCCH”, and “PDDCH” may be proposed as an example of “controlinformation”. In addition, even when shown as “control information(i.e., PDCCH)”, “PDCCH” may be proposed as an example of “controlinformation”.

Technical features that are separately described in one drawing in thepresent disclosure may be implemented separately or simultaneously.

Although not limited thereto, various descriptions, functions,procedures, suggestions, methods and/or operational flowcharts of thepresent disclosure disclosed herein can be applied to various fieldsrequiring wireless communication and/or connection (e.g., 5G) betweendevices.

Hereinafter, the present disclosure will be described in more detailwith reference to drawings. The same reference numerals in the followingdrawings and/or descriptions may refer to the same and/or correspondinghardware blocks, software blocks, and/or functional blocks unlessotherwise indicated.

FIG. 1 shows an example of a communication system to whichimplementations of the present disclosure is applied.

The 5G usage scenarios shown in FIG. 1 are only exemplary, and thetechnical features of the present disclosure can be applied to other 5Gusage scenarios which are not shown in FIG. 1.

Three main requirement categories for 5G include (1) a category ofenhanced mobile broadband (eMBB), (2) a category of massive machine typecommunication (mMTC), and (3) a category of ultra-reliable and lowlatency communications (URLLC).

Partial use cases may require a plurality of categories for optimizationand other use cases may focus only upon one key performance indicator(KPI). 5G supports such various use cases using a flexible and reliablemethod.

eMBB far surpasses basic mobile Internet access and covers abundantbidirectional work and media and entertainment applications in cloud andaugmented reality. Data is one of 5G core motive forces and, in a 5Gera, a dedicated voice service may not be provided for the first time.In 5G, it is expected that voice will be simply processed as anapplication program using data connection provided by a communicationsystem. Main causes for increased traffic volume are due to an increasein the size of content and an increase in the number of applicationsrequiring high data transmission rate. A streaming service (of audio andvideo), conversational video, and mobile Internet access will be morewidely used as more devices are connected to the Internet. These manyapplication programs require connectivity of an always turned-on statein order to push real-time information and alarm for users. Cloudstorage and applications are rapidly increasing in a mobilecommunication platform and may be applied to both work andentertainment. The cloud storage is a special use case which acceleratesgrowth of uplink data transmission rate. 5G is also used for remote workof cloud. When a tactile interface is used, 5G demands much lowerend-to-end latency to maintain user good experience. Entertainment, forexample, cloud gaming and video streaming, is another core element whichincreases demand for mobile broadband capability. Entertainment isessential for a smartphone and a tablet in any place including highmobility environments such as a train, a vehicle, and an airplane. Otheruse cases are augmented reality for entertainment and informationsearch. In this case, the augmented reality requires very low latencyand instantaneous data volume.

In addition, one of the most expected 5G use cases relates a functioncapable of smoothly connecting embedded sensors in all fields, i.e.,mMTC. It is expected that the number of potential Internet-of-things(IoT) devices will reach 204 hundred million up to the year of 2020. Anindustrial IoT is one of categories of performing a main role enabling asmart city, asset tracking, smart utility, agriculture, and securityinfrastructure through 5G.

URLLC includes a new service that will change industry through remotecontrol of main infrastructure and an ultra-reliable/availablelow-latency link such as a self-driving vehicle. A level of reliabilityand latency is essential to control a smart grid, automatize industry,achieve robotics, and control and adjust a drone.

5G is a means of providing streaming evaluated as a few hundred megabitsper second to gigabits per second and may complement fiber-to-the-home(FTTH) and cable-based broadband (or DOCSIS). Such fast speed is neededto deliver TV in resolution of 4K or more (6K, 8K, and more), as well asvirtual reality and augmented reality. Virtual reality (VR) andaugmented reality (AR) applications include almost immersive sportsgames. A specific application program may require a special networkconfiguration. For example, for VR games, gaming companies need toincorporate a core server into an edge network server of a networkoperator in order to minimize latency.

Automotive is expected to be a new important motivated force in 5Gtogether with many use cases for mobile communication for vehicles. Forexample, entertainment for passengers requires high simultaneouscapacity and mobile broadband with high mobility. This is because futureusers continue to expect connection of high quality regardless of theirlocations and speeds. Another use case of an automotive field is an ARdashboard. The AR dashboard causes a driver to identify an object in thedark in addition to an object seen from a front window and displays adistance from the object and a movement of the object by overlappinginformation talking to the driver. In the future, a wireless moduleenables communication between vehicles, information exchange between avehicle and supporting infrastructure, and information exchange betweena vehicle and other connected devices (e.g., devices accompanied by apedestrian). A safety system guides alternative courses of a behavior sothat a driver may drive more safely drive, thereby lowering the dangerof an accident. The next stage will be a remotely controlled orself-driven vehicle. This requires very high reliability and very fastcommunication between different self-driven vehicles and between avehicle and infrastructure. In the future, a self-driven vehicle willperform all driving activities and a driver will focus only uponabnormal traffic that the vehicle cannot identify. Technicalrequirements of a self-driven vehicle demand ultra-low latency andultra-high reliability so that traffic safety is increased to a levelthat cannot be achieved by human being.

A smart city and a smart home/building mentioned as a smart society willbe embedded in a high-density wireless sensor network. A distributednetwork of an intelligent sensor will identify conditions for costs andenergy-efficient maintenance of a city or a home Similar configurationsmay be performed for respective households. All of temperature sensors,window and heating controllers, burglar alarms, and home appliances arewirelessly connected. Many of these sensors are typically low in datatransmission rate, power, and cost. However, real-time HD video may bedemanded by a specific type of device to perform monitoring.

Consumption and distribution of energy including heat or gas isdistributed at a higher level so that automated control of thedistribution sensor network is demanded. The smart grid collectsinformation and connects the sensors to each other using digitalinformation and communication technology so as to act according to thecollected information. Since this information may include behaviors of asupply company and a consumer, the smart grid may improve distributionof fuels such as electricity by a method having efficiency, reliability,economic feasibility, production sustainability, and automation. Thesmart grid may also be regarded as another sensor network having lowlatency.

Mission critical application (e.g., e-health) is one of 5G usescenarios. A health part contains many application programs capable ofenjoying benefit of mobile communication. A communication system maysupport remote treatment that provides clinical treatment in a farawayplace. Remote treatment may aid in reducing a barrier against distanceand improve access to medical services that cannot be continuouslyavailable in a faraway rural area. Remote treatment is also used toperform important treatment and save lives in an emergency situation.The wireless sensor network based on mobile communication may provideremote monitoring and sensors for parameters such as heart rate andblood pressure.

Wireless and mobile communication gradually becomes important in thefield of an industrial application. Wiring is high in installation andmaintenance cost. Therefore, a possibility of replacing a cable withreconstructible wireless links is an attractive opportunity in manyindustrial fields. However, in order to achieve this replacement, it isnecessary for wireless connection to be established with latency,reliability, and capacity similar to those of the cable and managementof wireless connection needs to be simplified. Low latency and a verylow error probability are new requirements when connection to 5G isneeded.

Logistics and freight tracking are important use cases for mobilecommunication that enables inventory and package tracking anywhere usinga location-based information system. The use cases of logistics andfreight typically demand low data rate but require location informationwith a wide range and reliability.

Referring to FIG. 1, the communication system 1 includes wirelessdevices 100 a to 100 f, base stations (BSs) 200, and a network 300.Although FIG. 1 illustrates a 5G network as an example of the network ofthe communication system 1, the implementations of the presentdisclosure are not limited to the 5G system, and can be applied to thefuture communication system beyond the 5G system.

The BSs 200 and the network 300 may be implemented as wireless devicesand a specific wireless device may operate as a BS/network node withrespect to other wireless devices.

The wireless devices 100 a to 100 f represent devices performingcommunication using radio access technology (RAT) (e.g., 5G new RAT(NR)) or LTE) and may be referred to as communication/radio/5G devices.The wireless devices 100 a to 100 f may include, without being limitedto, a robot 100 a, vehicles 100 b-1 and 100 b-2, an extended reality(XR) device 100 c, a hand-held device 100 d, a home appliance 100 e, anIoT device 100 f, and an artificial intelligence (AI) device/server 400.For example, the vehicles may include a vehicle having a wirelesscommunication function, an autonomous driving vehicle, and a vehiclecapable of performing communication between vehicles. The vehicles mayinclude an unmanned aerial vehicle (UAV) (e.g., a drone). The XR devicemay include an AR/VR/Mixed Reality (MR) device and may be implemented inthe form of a head-mounted device (HMD), a head-up display (HUD) mountedin a vehicle, a television, a smartphone, a computer, a wearable device,a home appliance device, a digital signage, a vehicle, a robot, etc. Thehand-held device may include a smartphone, a smartpad, a wearable device(e.g., a smartwatch or a smartglasses), and a computer (e.g., anotebook). The home appliance may include a TV, a refrigerator, and awashing machine. The IoT device may include a sensor and a smartmeter.

In the present disclosure, the wireless devices 100 a to 100 f may becalled user equipments (UEs). A UE may include, for example, a cellularphone, a smartphone, a laptop computer, a digital broadcast terminal, apersonal digital assistant (PDA), a portable multimedia player (PMP), anavigation system, a slate personal computer (PC), a tablet PC, anultrabook, a vehicle, a vehicle having an autonomous traveling function,a connected car, an UAV, an AI module, a robot, an AR device, a VRdevice, an MR device, a hologram device, a public safety device, an MTCdevice, an IoT device, a medical device, a FinTech device (or afinancial device), a security device, a weather/environment device, adevice related to a 5G service, or a device related to a fourthindustrial revolution field.

The UAV may be, for example, an aircraft aviated by a wireless controlsignal without a human being onboard.

The VR device may include, for example, a device for implementing anobject or a background of the virtual world. The AR device may include,for example, a device implemented by connecting an object or abackground of the virtual world to an object or a background of the realworld. The MR device may include, for example, a device implemented bymerging an object or a background of the virtual world into an object ora background of the real world. The hologram device may include, forexample, a device for implementing a stereoscopic image of 360 degreesby recording and reproducing stereoscopic information, using aninterference phenomenon of light generated when two laser lights calledholography meet.

The public safety device may include, for example, an image relay deviceor an image device that is wearable on the body of a user.

The MTC device and the IoT device may be, for example, devices that donot require direct human intervention or manipulation. For example, theMTC device and the IoT device may include smartmeters, vending machines,thermometers, smartbulbs, door locks, or various sensors.

The medical device may be, for example, a device used for the purpose ofdiagnosing, treating, relieving, curing, or preventing disease. Forexample, the medical device may be a device used for the purpose ofdiagnosing, treating, relieving, or correcting injury or impairment. Forexample, the medical device may be a device used for the purpose ofinspecting, replacing, or modifying a structure or a function. Forexample, the medical device may be a device used for the purpose ofadjusting pregnancy. For example, the medical device may include adevice for treatment, a device for operation, a device for (in vitro)diagnosis, a hearing aid, or a device for procedure.

The security device may be, for example, a device installed to prevent adanger that may arise and to maintain safety. For example, the securitydevice may be a camera, a closed-circuit TV (CCTV), a recorder, or ablack box.

The FinTech device may be, for example, a device capable of providing afinancial service such as mobile payment. For example, the FinTechdevice may include a payment device or a point of sales (POS) system.

The weather/environment device may include, for example, a device formonitoring or predicting a weather/environment.

The wireless devices 100 a to 100 f may be connected to the network 300via the BSs 200. An AI technology may be applied to the wireless devices100 a to 100 f and the wireless devices 100 a to 100 f may be connectedto the AI server 400 via the network 300. The network 300 may beconfigured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR)network, and a beyond-5G network. Although the wireless devices 100 a to100 f may communicate with each other through the BSs 200/network 300,the wireless devices 100 a to 100 f may perform direct communication(e.g., sidelink communication) with each other without passing throughthe BSs 200/network 300. For example, the vehicles 100 b-1 and 100 b-2may perform direct communication (e.g. vehicle-to-vehicle(V2V)/vehicle-to-everything (V2X) communication). The IoT device (e.g.,a sensor) may perform direct communication with other IoT devices (e.g.,sensors) or other wireless devices 100 a to 100 f.

Wireless communication/connections 150 a, 150 b and 150 c may beestablished between the wireless devices 100 a to 100 f and/or betweenwireless device 100 a to 100 f and BS 200 and/or between BSs 200.Herein, the wireless communication/connections may be establishedthrough various RATs (e.g., 5G NR) such as uplink/downlink communication150 a, sidelink communication (or device-to-device (D2D) communication)150 b, inter-base station communication 150 c (e.g., relay, integratedaccess and backhaul (IAB)), etc. The wireless devices 100 a to 100 f andthe BSs 200/the wireless devices 100 a to 100 f may transmit/receiveradio signals to/from each other through the wirelesscommunication/connections 150 a, 150 b and 150 c. For example, thewireless communication/connections 150 a, 150 b and 150 c maytransmit/receive signals through various physical channels. To this end,at least a part of various configuration information configuringprocesses, various signal processing processes (e.g., channelencoding/decoding, modulation/demodulation, and resourcemapping/de-mapping), and resource allocating processes, fortransmitting/receiving radio signals, may be performed based on thevarious proposals of the present disclosure.

FIG. 2 shows an example of wireless devices to which implementations ofthe present disclosure is applied.

Referring to FIG. 2, a first wireless device 100 and a second wirelessdevice 200 may transmit/receive radio signals to/from an external devicethrough a variety of RATs (e.g., LTE and NR). In FIG. 2, {the firstwireless device 100 and the second wireless device 200} may correspondto at least one of {the wireless device 100 a to 100 f and the BS 200},{the wireless device 100 a to 100 f and the wireless device 100 a to 100f} and/or {the BS 200 and the BS 200} of FIG. 1.

The first wireless device 100 may include one or more processors 102 andone or more memories 104 and additionally further include one or moretransceivers 106 and/or one or more antennas 108. The processor(s) 102may control the memory(s) 104 and/or the transceiver(s) 106 and may beconfigured to implement the descriptions, functions, procedures,suggestions, methods and/or operational flowcharts described in thepresent disclosure. For example, the processor(s) 102 may processinformation within the memory(s) 104 to generate firstinformation/signals and then transmit radio signals including the firstinformation/signals through the transceiver(s) 106. The processor(s) 102may receive radio signals including second information/signals throughthe transceiver(s) 106 and then store information obtained by processingthe second information/signals in the memory(s) 104. The memory(s) 104may be connected to the processor(s) 102 and may store a variety ofinformation related to operations of the processor(s) 102. For example,the memory(s) 104 may store software code including commands forperforming a part or the entirety of processes controlled by theprocessor(s) 102 or for performing the descriptions, functions,procedures, suggestions, methods and/or operational flowcharts describedin the present disclosure. Herein, the processor(s) 102 and thememory(s) 104 may be a part of a communication modem/circuit/chipdesigned to implement RAT (e.g., LTE or NR). The transceiver(s) 106 maybe connected to the processor(s) 102 and transmit and/or receive radiosignals through one or more antennas 108. Each of the transceiver(s) 106may include a transmitter and/or a receiver. The transceiver(s) 106 maybe interchangeably used with radio frequency (RF) unit(s). In thepresent disclosure, the first wireless device 100 may represent acommunication modem/circuit/chip.

The second wireless device 200 may include one or more processors 202and one or more memories 204 and additionally further include one ormore transceivers 206 and/or one or more antennas 208. The processor(s)202 may control the memory(s) 204 and/or the transceiver(s) 206 and maybe configured to implement the descriptions, functions, procedures,suggestions, methods and/or operational flowcharts described in thepresent disclosure. For example, the processor(s) 202 may processinformation within the memory(s) 204 to generate thirdinformation/signals and then transmit radio signals including the thirdinformation/signals through the transceiver(s) 206. The processor(s) 202may receive radio signals including fourth information/signals throughthe transceiver(s) 106 and then store information obtained by processingthe fourth information/signals in the memory(s) 204. The memory(s) 204may be connected to the processor(s) 202 and may store a variety ofinformation related to operations of the processor(s) 202. For example,the memory(s) 204 may store software code including commands forperforming a part or the entirety of processes controlled by theprocessor(s) 202 or for performing the descriptions, functions,procedures, suggestions, methods and/or operational flowcharts describedin the present disclosure. Herein, the processor(s) 202 and thememory(s) 204 may be a part of a communication modem/circuit/chipdesigned to implement RAT (e.g., LTE or NR). The transceiver(s) 206 maybe connected to the processor(s) 202 and transmit and/or receive radiosignals through one or more antennas 208. Each of the transceiver(s) 206may include a transmitter and/or a receiver. The transceiver(s) 206 maybe interchangeably used with RF unit(s). In the present disclosure, thesecond wireless device 200 may represent a communicationmodem/circuit/chip.

Hereinafter, hardware elements of the wireless devices 100 and 200 willbe described more specifically. One or more protocol layers may beimplemented by, without being limited to, one or more processors 102 and202. For example, the one or more processors 102 and 202 may implementone or more layers (e.g., functional layers such as physical (PHY)layer, media access control (MAC) layer, radio link control (RLC) layer,packet data convergence protocol (PDCP) layer, radio resource control(RRC) layer, and service data adaptation protocol (SDAP) layer). The oneor more processors 102 and 202 may generate one or more protocol dataunits (PDUs) and/or one or more service data unit (SDUs) according tothe descriptions, functions, procedures, suggestions, methods and/oroperational flowcharts disclosed in the present disclosure. The one ormore processors 102 and 202 may generate messages, control information,data, or information according to the descriptions, functions,procedures, suggestions, methods and/or operational flowcharts disclosedin the present disclosure. The one or more processors 102 and 202 maygenerate signals (e.g., baseband signals) including PDUs, SDUs,messages, control information, data, or information according to thedescriptions, functions, procedures, suggestions, methods and/oroperational flowcharts disclosed in the present disclosure and providethe generated signals to the one or more transceivers 106 and 206. Theone or more processors 102 and 202 may receive the signals (e.g.,baseband signals) from the one or more transceivers 106 and 206 andacquire the PDUs, SDUs, messages, control information, data, orinformation according to the descriptions, functions, procedures,suggestions, methods and/or operational flowcharts disclosed in thepresent disclosure.

The one or more processors 102 and 202 may be referred to ascontrollers, microcontrollers, microprocessors, or microcomputers. Theone or more processors 102 and 202 may be implemented by hardware,firmware, software, or a combination thereof. As an example, one or moreapplication specific integrated circuits (ASICs), one or more digitalsignal processors (DSPs), one or more digital signal processing devices(DSPDs), one or more programmable logic devices (PLDs), or one or morefield programmable gate arrays (FPGAs) may be included in the one ormore processors 102 and 202. descriptions, functions, procedures,suggestions, methods and/or operational flowcharts disclosed in thepresent disclosure may be implemented using firmware or software and thefirmware or software may be configured to include the modules,procedures, or functions. Firmware or software configured to perform thedescriptions, functions, procedures, suggestions, methods and/oroperational flowcharts disclosed in the present disclosure may beincluded in the one or more processors 102 and 202 or stored in the oneor more memories 104 and 204 so as to be driven by the one or moreprocessors 102 and 202. The descriptions, functions, procedures,suggestions, methods and/or operational flowcharts disclosed in thepresent disclosure may be implemented using firmware or software in theform of code, commands, and/or a set of command.

The one or more memories 104 and 204 may be connected to the one or moreprocessors 102 and 202 and store various types of data, signals,messages, information, programs, code, instructions, and/or commands.The one or more memories 104 and 204 may be configured by read-onlymemories (ROMs), random access memories (RAMs), electrically erasableprogrammable read-only memories (EPROMs), flash memories, hard drives,registers, cash memories, computer-readable storage media, and/orcombinations thereof. The one or more memories 104 and 204 may belocated at the interior and/or exterior of the one or more processors102 and 202. The one or more memories 104 and 204 may be connected tothe one or more processors 102 and 202 through various technologies suchas wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, controlinformation, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, suggestions, methods and/oroperational flowcharts disclosed in the present disclosure, to one ormore other devices. The one or more transceivers 106 and 206 may receiveuser data, control information, and/or radio signals/channels, mentionedin the descriptions, functions, procedures, suggestions, methods and/oroperational flowcharts disclosed in the present disclosure, from one ormore other devices. For example, the one or more transceivers 106 and206 may be connected to the one or more processors 102 and 202 andtransmit and receive radio signals. For example, the one or moreprocessors 102 and 202 may perform control so that the one or moretransceivers 106 and 206 may transmit user data, control information, orradio signals to one or more other devices. The one or more processors102 and 202 may perform control so that the one or more transceivers 106and 206 may receive user data, control information, or radio signalsfrom one or more other devices.

The one or more transceivers 106 and 206 may be connected to the one ormore antennas 108 and 208 and the one or more transceivers 106 and 206may be configured to transmit and receive user data, controlinformation, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, suggestions, methods and/oroperational flowcharts disclosed in the present disclosure, through theone or more antennas 108 and 208. In the present disclosure, the one ormore antennas may be a plurality of physical antennas or a plurality oflogical antennas (e.g., antenna ports).

The one or more transceivers 106 and 206 may convert received radiosignals/channels, etc., from RF band signals into baseband signals inorder to process received user data, control information, radiosignals/channels, etc., using the one or more processors 102 and 202.The one or more transceivers 106 and 206 may convert the user data,control information, radio signals/channels, etc., processed using theone or more processors 102 and 202 from the base band signals into theRF band signals. To this end, the one or more transceivers 106 and 206may include (analog) oscillators and/or filters. For example, thetransceivers 106 and 206 can up-convert OFDM baseband signals to acarrier frequency by their (analog) oscillators and/or filters under thecontrol of the processors 102 and 202 and transmit the up-converted OFDMsignals at the carrier frequency. The transceivers 106 and 206 mayreceive OFDM signals at a carrier frequency and down-convert the OFDMsignals into OFDM baseband signals by their (analog) oscillators and/orfilters under the control of the transceivers 102 and 202.

In the implementations of the present disclosure, a UE may operate as atransmitting device in uplink (UL) and as a receiving device in downlink(DL). In the implementations of the present disclosure, a BS may operateas a receiving device in UL and as a transmitting device in DL.Hereinafter, for convenience of description, it is mainly assumed thatthe first wireless device 100 acts as the UE, and the second wirelessdevice 200 acts as the BS. For example, the processor(s) 102 connectedto, mounted on or launched in the first wireless device 100 may beconfigured to perform the UE behavior according to an implementation ofthe present disclosure or control the transceiver(s) 106 to perform theUE behavior according to an implementation of the present disclosure.The processor(s) 202 connected to, mounted on or launched in the secondwireless device 200 may be configured to perform the BS behavioraccording to an implementation of the present disclosure or control thetransceiver(s) 206 to perform the BS behavior according to animplementation of the present disclosure.

In the present disclosure, a BS is also referred to as a node B (NB), aneNode B (eNB), or a gNB.

FIG. 3 shows an example of a wireless device to which implementations ofthe present disclosure is applied.

The wireless device may be implemented in various forms according to ause-case/service (refer to FIG. 1).

Referring to FIG. 3, wireless devices 100 and 200 may correspond to thewireless devices 100 and 200 of FIG. 2 and may be configured by variouselements, components, units/portions, and/or modules. For example, eachof the wireless devices 100 and 200 may include a communication unit110, a control unit 120, a memory unit 130, and additional components140. The communication unit 110 may include a communication circuit 112and transceiver(s) 114. For example, the communication circuit 112 mayinclude the one or more processors 102 and 202 of FIG. 2 and/or the oneor more memories 104 and 204 of FIG. 2. For example, the transceiver(s)114 may include the one or more transceivers 106 and 206 of FIG. 2and/or the one or more antennas 108 and 208 of FIG. 2. The control unit120 is electrically connected to the communication unit 110, the memory130, and the additional components 140 and controls overall operation ofeach of the wireless devices 100 and 200. For example, the control unit120 may control an electric/mechanical operation of each of the wirelessdevices 100 and 200 based on programs/code/commands/information storedin the memory unit 130. The control unit 120 may transmit theinformation stored in the memory unit 130 to the exterior (e.g., othercommunication devices) via the communication unit 110 through awireless/wired interface or store, in the memory unit 130, informationreceived through the wireless/wired interface from the exterior (e.g.,other communication devices) via the communication unit 110.

The additional components 140 may be variously configured according totypes of the wireless devices 100 and 200. For example, the additionalcomponents 140 may include at least one of a power unit/battery,input/output (I/O) unit (e.g., audio I/O port, video I/O port), adriving unit, and a computing unit. The wireless devices 100 and 200 maybe implemented in the form of, without being limited to, the robot (100a of FIG. 1), the vehicles (100 b-1 and 100 b-2 of FIG. 1), the XRdevice (100 c of FIG. 1), the hand-held device (100 d of FIG. 1), thehome appliance (100 e of FIG. 1), the IoT device (100 f of FIG. 1), adigital broadcast terminal, a hologram device, a public safety device,an MTC device, a medicine device, a FinTech device (or a financedevice), a security device, a climate/environment device, the AIserver/device (400 of FIG. 1), the BSs (200 of FIG. 1), a network node,etc. The wireless devices 100 and 200 may be used in a mobile or fixedplace according to a use-example/service.

In FIG. 3, the entirety of the various elements, components,units/portions, and/or modules in the wireless devices 100 and 200 maybe connected to each other through a wired interface or at least a partthereof may be wirelessly connected through the communication unit 110.For example, in each of the wireless devices 100 and 200, the controlunit 120 and the communication unit 110 may be connected by wire and thecontrol unit 120 and first units (e.g., 130 and 140) may be wirelesslyconnected through the communication unit 110. Each element, component,unit/portion, and/or module within the wireless devices 100 and 200 mayfurther include one or more elements. For example, the control unit 120may be configured by a set of one or more processors. As an example, thecontrol unit 120 may be configured by a set of a communication controlprocessor, an application processor (AP), an electronic control unit(ECU), a graphical processing unit, and a memory control processor. Asanother example, the memory 130 may be configured by a RAM, a DRAM, aROM, a flash memory, a volatile memory, a non-volatile memory, and/or acombination thereof.

FIG. 4 shows another example of wireless devices to whichimplementations of the present disclosure is applied.

Referring to FIG. 4, wireless devices 100 and 200 may correspond to thewireless devices 100 and 200 of FIG. 2 and may be configured by variouselements, components, units/portions, and/or modules.

The first wireless device 100 may include at least one transceiver, suchas a transceiver 106, and at least one processing chip, such as aprocessing chip 101. The processing chip 101 may include at least oneprocessor, such a processor 102, and at least one memory, such as amemory 104. The memory 104 may be operably connectable to the processor102. The memory 104 may store various types of information and/orinstructions. The memory 104 may store a software code 105 whichimplements instructions that, when executed by the processor 102,perform the descriptions, functions, procedures, suggestions, methodsand/or operational flowcharts disclosed in the present disclosure. Forexample, the software code 105 may implement instructions that, whenexecuted by the processor 102, perform the descriptions, functions,procedures, suggestions, methods and/or operational flowcharts disclosedin the present disclosure. For example, the software code 105 maycontrol the processor 102 to perform one or more protocols. For example,the software code 105 may control the processor 102 may perform one ormore layers of the radio interface protocol.

The second wireless device 200 may include at least one transceiver,such as a transceiver 206, and at least one processing chip, such as aprocessing chip 201. The processing chip 201 may include at least oneprocessor, such a processor 202, and at least one memory, such as amemory 204. The memory 204 may be operably connectable to the processor202. The memory 204 may store various types of information and/orinstructions. The memory 204 may store a software code 205 whichimplements instructions that, when executed by the processor 202,perform the descriptions, functions, procedures, suggestions, methodsand/or operational flowcharts disclosed in the present disclosure. Forexample, the software code 205 may implement instructions that, whenexecuted by the processor 202, perform the descriptions, functions,procedures, suggestions, methods and/or operational flowcharts disclosedin the present disclosure. For example, the software code 205 maycontrol the processor 202 to perform one or more protocols. For example,the software code 205 may control the processor 202 may perform one ormore layers of the radio interface protocol.

FIG. 5 shows an example of UE to which implementations of the presentdisclosure is applied.

Referring to FIG. 5, a UE 100 may correspond to the first wirelessdevice 100 of FIG. 2 and/or the first wireless device 100 of FIG. 4.

A UE 100 includes a processor 102, a memory 104, a transceiver 106, oneor more antennas 108, a power management module 110, a battery 1112, adisplay 114, a keypad 116, a subscriber identification module (SIM) card118, a speaker 120, and a microphone 122.

The processor 102 may be configured to implement the descriptions,functions, procedures, suggestions, methods and/or operationalflowcharts disclosed in the present disclosure. The processor 102 may beconfigured to control one or more other components of the UE 100 toimplement the descriptions, functions, procedures, suggestions, methodsand/or operational flowcharts disclosed in the present disclosure.Layers of the radio interface protocol may be implemented in theprocessor 102. The processor 102 may include ASIC, other chipset, logiccircuit and/or data processing device. The processor 102 may be anapplication processor. The processor 102 may include at least one of adigital signal processor (DSP), a central processing unit (CPU), agraphics processing unit (GPU), a modem (modulator and demodulator). Anexample of the processor 102 may be found in SNAPDRAGON™ series ofprocessors made by Qualcomm®, EXYNOS™ series of processors made bySamsung®, A series of processors made by Apple®, HELIO™ series ofprocessors made by MediaTek®, ATOM™ series of processors made by Intel®or a corresponding next generation processor.

The memory 104 is operatively coupled with the processor 102 and storesa variety of information to operate the processor 102. The memory 104may include ROM, RAM, flash memory, memory card, storage medium and/orother storage device. When the embodiments are implemented in software,the techniques described herein can be implemented with modules (e.g.,procedures, functions, etc.) that perform the descriptions, functions,procedures, suggestions, methods and/or operational flowcharts disclosedin the present disclosure. The modules can be stored in the memory 104and executed by the processor 102. The memory 104 can be implementedwithin the processor 102 or external to the processor 102 in which casethose can be communicatively coupled to the processor 102 via variousmeans as is known in the art.

The transceiver 106 is operatively coupled with the processor 102, andtransmits and/or receives a radio signal. The transceiver 106 includes atransmitter and a receiver. The transceiver 106 may include basebandcircuitry to process radio frequency signals. The transceiver 106controls the one or more antennas 108 to transmit and/or receive a radiosignal.

The power management module 110 manages power for the processor 102and/or the transceiver 106. The battery 112 supplies power to the powermanagement module 110.

The display 114 outputs results processed by the processor 102. Thekeypad 116 receives inputs to be used by the processor 102. The keypad16 may be shown on the display 114.

The SIM card 118 is an integrated circuit that is intended to securelystore the international mobile subscriber identity (IMSI) number and itsrelated key, which are used to identify and authenticate subscribers onmobile telephony devices (such as mobile phones and computers). It isalso possible to store contact information on many SIM cards.

The speaker 120 outputs sound-related results processed by the processor102. The microphone 122 receives sound-related inputs to be used by theprocessor 102.

FIGS. 6 and 7 show an example of protocol stacks in a 3GPP basedwireless communication system to which implementations of the presentdisclosure is applied.

In particular, FIG. 6 illustrates an example of a radio interface userplane protocol stack between a UE and a BS and FIG. 7 illustrates anexample of a radio interface control plane protocol stack between a UEand a BS. The control plane refers to a path through which controlmessages used to manage call by a UE and a network are transported. Theuser plane refers to a path through which data generated in anapplication layer, for example, voice data or Internet packet data aretransported.

Referring to FIG. 6, the user plane protocol stack may be divided intoLayer 1 (i.e., a PHY layer) and Layer 2. Referring to FIG. 7, thecontrol plane protocol stack may be divided into Layer 1 (i.e., a PHYlayer), Layer 2, Layer 3 (e.g., an RRC layer), and a non-access stratum(NAS) layer. Layer 1, Layer 2 and Layer 3 are referred to as an accessstratum (AS).

In the 3GPP LTE system, the Layer 2 is split into the followingsublayers: MAC, RLC, and PDCP. In the 3GPP NR system, the Layer 2 issplit into the following sublayers: MAC, RLC, PDCP and SDAP. The PHYlayer offers to the MAC sublayer transport channels, the MAC sublayeroffers to the RLC sublayer logical channels, the RLC sublayer offers tothe PDCP sublayer RLC channels, the PDCP sublayer offers to the SDAPsublayer radio bearers. The SDAP sublayer offers to 5G core networkquality of service (QoS) flows.

In the 3GPP NR system, the main services and functions of the MACsublayer include: mapping between logical channels and transportchannels; multiplexing/de-multiplexing of MAC SDUs belonging to one ordifferent logical channels into/from transport blocks (TB) deliveredto/from the physical layer on transport channels; scheduling informationreporting; error correction through hybrid automatic repeat request(HARQ) (one HARQ entity per cell in case of carrier aggregation (CA));priority handling between UEs by means of dynamic scheduling; priorityhandling between logical channels of one UE by means of logical channelprioritization; padding. A single MAC entity may support multiplenumerologies, transmission timings and cells. Mapping restrictions inlogical channel prioritization control which numerology(ies), cell(s),and transmission timing(s) a logical channel can use.

Different kinds of data transfer services are offered by MAC. Toaccommodate different kinds of data transfer services, multiple types oflogical channels are defined, i.e., each supporting transfer of aparticular type of information. Each logical channel type is defined bywhat type of information is transferred. Logical channels are classifiedinto two groups: control channels and traffic channels. Control channelsare used for the transfer of control plane information only, and trafficchannels are used for the transfer of user plane information only.Broadcast control channel (BCCH) is a downlink logical channel forbroadcasting system control information, paging control channel (PCCH)is a downlink logical channel that transfers paging information, systeminformation change notifications and indications of ongoing publicwarning service (PWS) broadcasts, common control channel (CCCH) is alogical channel for transmitting control information between UEs andnetwork and used for UEs having no RRC connection with the network, anddedicated control channel (DCCH) is a point-to-point bi-directionallogical channel that transmits dedicated control information between aUE and the network and used by UEs having an RRC connection. Dedicatedtraffic channel (DTCH) is a point-to-point logical channel, dedicated toone UE, for the transfer of user information. A DTCH can exist in bothuplink and downlink. In downlink, the following connections betweenlogical channels and transport channels exist: BCCH can be mapped tobroadcast channel (BCH); BCCH can be mapped to downlink shared channel(DL-SCH); PCCH can be mapped to paging channel (PCH); CCCH can be mappedto DL-SCH; DCCH can be mapped to DL-SCH; and DTCH can be mapped toDL-SCH. In uplink, the following connections between logical channelsand transport channels exist: CCCH can be mapped to uplink sharedchannel (UL-SCH); DCCH can be mapped to UL-SCH; and DTCH can be mappedto UL-SCH.

The RLC sublayer supports three transmission modes: transparent mode(TM), unacknowledged mode (UM), and acknowledged node (AM). The RLCconfiguration is per logical channel with no dependency on numerologiesand/or transmission durations. In the 3GPP NR system, the main servicesand functions of the RLC sublayer depend on the transmission mode andinclude: transfer of upper layer PDUs; sequence numbering independent ofthe one in PDCP (UM and AM); error correction through ARQ (AM only);segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs;reassembly of SDU (AM and UM); duplicate detection (AM only); RLC SDUdiscard (AM and UM); RLC re-establishment; protocol error detection (AMonly).

In the 3GPP NR system, the main services and functions of the PDCPsublayer for the user plane include: sequence numbering; headercompression and decompression using robust header compression (ROHC);transfer of user data; reordering and duplicate detection; in-orderdelivery; PDCP PDU routing (in case of split bearers); retransmission ofPDCP SDUs; ciphering, deciphering and integrity protection; PDCP SDUdiscard; PDCP re-establishment and data recovery for RLC AM; PDCP statusreporting for RLC AM; duplication of PDCP PDUs and duplicate discardindication to lower layers. The main services and functions of the PDCPsublayer for the control plane include: sequence numbering; ciphering,deciphering and integrity protection; transfer of control plane data;reordering and duplicate detection; in-order delivery; duplication ofPDCP PDUs and duplicate discard indication to lower layers.

In the 3GPP NR system, the main services and functions of SDAP include:mapping between a QoS flow and a data radio bearer; marking QoS flow ID(QFI) in both DL and UL packets. A single protocol entity of SDAP isconfigured for each individual PDU session.

In the 3GPP NR system, the main services and functions of the RRCsublayer include: broadcast of system information related to AS and NAS;paging initiated by 5GC or NG-RAN; establishment, maintenance andrelease of an RRC connection between the UE and NG-RAN; securityfunctions including key management; establishment, configuration,maintenance and release of signaling radio bearers (SRBs) and data radiobearers (DRBs); mobility functions (including: handover and contexttransfer, UE cell selection and reselection and control of cellselection and reselection, inter-RAT mobility); QoS managementfunctions; UE measurement reporting and control of the reporting;detection of and recovery from radio link failure; NAS message transferto/from NAS from/to UE.

FIG. 8 shows a frame structure in a 3GPP based wireless communicationsystem to which implementations of the present disclosure is applied.

The frame structure shown in FIG. 8 is purely exemplary and the numberof subframes, the number of slots, and/or the number of symbols in aframe may be variously changed. In the 3GPP based wireless communicationsystem, OFDM numerologies (e.g., subcarrier spacing (SCS), transmissiontime interval (TTI) duration) may be differently configured between aplurality of cells aggregated for one UE. For example, if a UE isconfigured with different SCSs for cells aggregated for the cell, an(absolute time) duration of a time resource (e.g., a subframe, a slot,or a TTI) including the same number of symbols may be different amongthe aggregated cells. Herein, symbols may include OFDM symbols (orCP-OFDM symbols), SC-FDMA symbols (or discrete Fouriertransform-spread-OFDM (DFT-s-OFDM) symbols).

Referring to FIG. 8, downlink and uplink transmissions are organizedinto frames. Each frame has T_(f)=10 ms duration. Each frame is dividedinto two half-frames, where each of the half-frames has 5 ms duration.Each half-frame consists of 5 subframes, where the duration T_(sf) persubframe is 1 ms. Each subframe is divided into slots and the number ofslots in a subframe depends on a subcarrier spacing. Each slot includes14 or 12 OFDM symbols based on a cyclic prefix (CP). In a normal CP,each slot includes 14 OFDM symbols and, in an extended CP, each slotincludes 12 OFDM symbols. The numerology is based on exponentiallyscalable subcarrier spacing βf=2^(u)*15 kHz.

Table 1 shows the number of OFDM symbols per slot N^(slot) _(symb), thenumber of slots per frame N^(frame,u) _(slot), and the number of slotsper subframe N^(subframe,u) _(slot) for the normal CP, according to thesubcarrier spacing Δf=2^(u)*15 kHz.

TABLE 1 u N^(slot) _(symb) N^(frame, u) _(slot) N^(subframe, u) _(slot)0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

Table 2 shows the number of OFDM symbols per slot N^(slot) _(symb), thenumber of slots per frame N^(frame,u) _(slot), and the number of slotsper subframe N^(subframe,u) _(slot) for the extended CP, according tothe subcarrier spacing Δf=2^(u)*15 kHz.

TABLE 2 u N^(slot) _(symb) N^(frame, u) _(slot) N^(subframe, u) _(slot)2 12 40 4

A slot includes plural symbols (e.g., 14 or 12 symbols) in the timedomain. For each numerology (e.g., subcarrier spacing) and carrier, aresource grid of N^(size,u) _(grid,x)*N^(RB) _(sc) subcarriers andN^(subframe,u) _(symb) OFDM symbols is defined, starting at commonresource block (CRB) t^(start,u) _(grid) indicated by higher-layersignaling (e.g., RRC signaling), where N^(size,u) _(grid,x) is thenumber of resource blocks (RBs) in the resource grid and the subscript xis DL for downlink and UL for uplink. N^(RB) _(sc) is the number ofsubcarriers per RB. In the 3GPP based wireless communication system,N^(RB) _(sc) is 12 generally. There is one resource grid for a givenantenna port p, subcarrier spacing configuration u, and transmissiondirection (DL or UL). The carrier bandwidth N^(size,u) _(grid) forsubcarrier spacing configuration u is given by the higher-layerparameter (e.g., RRC parameter). Each element in the resource grid forthe antenna port p and the subcarrier spacing configuration u isreferred to as a resource element (RE) and one complex symbol may bemapped to each RE. Each RE in the resource grid is uniquely identifiedby an index k in the frequency domain and an index l representing asymbol location relative to a reference point in the time domain. In the3GPP based wireless communication system, an RB is defined by 12consecutive subcarriers in the frequency domain.

In the 3GPP NR system, RBs are classified into CRBs and physicalresource blocks (PRBs). CRBs are numbered from 0 and upwards in thefrequency domain for subcarrier spacing configuration u. The center ofsubcarrier 0 of CRB 0 for subcarrier spacing configuration u coincideswith ‘point A’ which serves as a common reference point for resourceblock grids. In the 3GPP NR system, PRBs are defined within a bandwidthpart (BWP) and numbered from 0 to N^(size) _(BWP,i)−1, where i is thenumber of the bandwidth part. The relation between the physical resourceblock n_(PRB) in the bandwidth part i and the common resource blockN_(CRB) is as Follows: n_(PRB)=n_(CRB)+N^(size) _(BWP) where N^(size)_(BWP,i) is the Common Resource Block where Bandwidth Part Startsrelative to CRB 0. The BWP includes a plurality of consecutive RBs. Acarrier may include a maximum of N (e.g., 5) BWPs. A UE may beconfigured with one or more BWPs on a given component carrier. Only oneBWP among BWPs configured to the UE can active at a time. The active BWPdefines the UE's operating bandwidth within the cell's operatingbandwidth.

The NR frequency band may be defined as two types of frequency range,i.e., FR1 and FR2. The numerical value of the frequency range may bechanged. For example, the frequency ranges of the two types (FR1 andFR2) may be as shown in Table 3 below. For ease of explanation, in thefrequency ranges used in the NR system, FR1 may mean “sub 6 GHz range”,FR2 may mean “above 6 GHz range,” and may be referred to as millimeterwave (mmW).

TABLE 3 Frequency Range Corresponding designation frequency rangeSubcarrier Spacing FR1  450 MHz-6000 MHz  15, 30, 60 kHz FR2 24250MHz-52600 MHz 60, 120, 240 kHz

As mentioned above, the numerical value of the frequency range of the NRsystem may be changed. For example, FR1 may include a frequency band of410 MHz to 7125 MHz as shown in Table 4 below. That is, FR1 may includea frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or more. Forexample, a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) ormore included in FR1 may include an unlicensed band. Unlicensed bandsmay be used for a variety of purposes, for example for communication forvehicles (e.g., autonomous driving).

TABLE 4 Frequency Range Corresponding designation frequency rangeSubcarrier Spacing FR1  410 MHz-7125 MHz  15, 30, 60 kHz FR2 24250MHz-52600 MHz 60, 120, 240 kHz

In the present disclosure, the term “cell” may refer to a geographicarea to which one or more nodes provide a communication system, or referto radio resources. A “cell” as a geographic area may be understood ascoverage within which a node can provide service using a carrier and a“cell” as radio resources (e.g., time-frequency resources) is associatedwith bandwidth which is a frequency range configured by the carrier. The“cell” associated with the radio resources is defined by a combinationof downlink resources and uplink resources, for example, a combinationof a DL component carrier (CC) and a UL CC. The cell may be configuredby downlink resources only, or may be configured by downlink resourcesand uplink resources. Since DL coverage, which is a range within whichthe node is capable of transmitting a valid signal, and UL coverage,which is a range within which the node is capable of receiving the validsignal from the UE, depends upon a carrier carrying the signal, thecoverage of the node may be associated with coverage of the “cell” ofradio resources used by the node. Accordingly, the term “cell” may beused to represent service coverage of the node sometimes, radioresources at other times, or a range that signals using the radioresources can reach with valid strength at other times.

In CA, two or more CCs are aggregated. A UE may simultaneously receiveor transmit on one or multiple CCs depending on its capabilities. CA issupported for both contiguous and non-contiguous CCs. When CA isconfigured, the UE only has one RRC connection with the network. At RRCconnection establishment/re-establishment/handover, one serving cellprovides the NAS mobility information, and at RRC connectionre-establishment/handover, one serving cell provides the security input.This cell is referred to as the primary cell (PCell). The PCell is acell, operating on the primary frequency, in which the UE eitherperforms the initial connection establishment procedure or initiates theconnection re-establishment procedure. Depending on UE capabilities,secondary cells (SCells) can be configured to form together with thePCell a set of serving cells. An SCell is a cell providing additionalradio resources on top of special cell (SpCell). The configured set ofserving cells for a UE therefore always consists of one PCell and one ormore SCells. For dual connectivity (DC) operation, the term SpCellrefers to the PCell of the master cell group (MCG) or the primary SCell(PSCell) of the secondary cell group (SCG). An SpCell supports PUCCHtransmission and contention-based random access, and is alwaysactivated. The MCG is a group of serving cells associated with a masternode, comprised of the SpCell (PCell) and optionally one or more SCells.The SCG is the subset of serving cells associated with a secondary node,comprised of the PSCell and zero or more SCells, for a UE configuredwith DC. For a UE in RRC_CONNECTED not configured with CA/DC, there isonly one serving cell comprised of the PCell. For a UE in RRC_CONNECTEDconfigured with CA/DC, the term “serving cells” is used to denote theset of cells comprised of the SpCell(s) and all SCells. In DC, two MACentities are configured in a UE: one for the MCG and one for the SCG.

FIG. 9 shows a data flow example in the 3GPP NR system to whichimplementations of the present disclosure is applied.

Referring to FIG. 9, “RB” denotes a radio bearer, and “H” denotes aheader. Radio bearers are categorized into two groups: DRBs for userplane data and SRBs for control plane data. The MAC PDU istransmitted/received using radio resources through the PHY layer to/froman external device. The MAC PDU arrives to the PHY layer in the form ofa transport block.

In the PHY layer, the uplink transport channels UL-SCH and RACH aremapped to their physical channels PUSCH and PRACH, respectively, and thedownlink transport channels DL-SCH, BCH and PCH are mapped to PDSCH,PBCH and PDSCH, respectively. In the PHY layer, uplink controlinformation (UCI) is mapped to PUCCH, and downlink control information(DCI) is mapped to PDCCH. A MAC PDU related to UL-SCH is transmitted bya UE via a PUSCH based on an UL grant, and a MAC PDU related to DL-SCHis transmitted by a BS via a PDSCH based on a DL assignment.

Support for vehicle-to-vehicle (V2V) and vehicle-to-everything (V2X)services has been introduced in LTE during Releases 14 and 15, in orderto expand the 3GPP platform to the automotive industry. These work itemsdefined an LTE sidelink suitable for vehicular applications, andcomplementary enhancements to the cellular infrastructure.

Further to this work, requirements for support of enhanced V2X use caseshave been defined in 5G LTE/NR, which are broadly arranged into four usecase groups:

1) Vehicles platooning enables the vehicles to dynamically form aplatoon travelling together. All the vehicles in the platoon obtaininformation from the leading vehicle to manage this platoon. Theseinformation allow the vehicles to drive closer than normal in acoordinated manner, going to the same direction and travelling together.

2) Extended Sensors enables the exchange of raw or processed datagathered through local sensors or live video images among vehicles, roadsite units, devices of pedestrian and V2X application servers. Thevehicles can increase the perception of their environment beyond of whattheir own sensors can detect and have a more broad and holistic view ofthe local situation. High data rate is one of the key characteristics.

3) Advanced driving enables semi-automated or full-automated driving.Each vehicle and/or RSU shares its own perception data obtained from itslocal sensors with vehicles in proximity and that allows vehicles tosynchronize and coordinate their trajectories or maneuvers. Each vehicleshares its driving intention with vehicles in proximity too.

4) Remote driving enables a remote driver or a V2X application tooperate a remote vehicle for those passengers who cannot drive bythemselves or remote vehicles located in dangerous environments. For acase where variation is limited and routes are predictable, such aspublic transportation, driving based on cloud computing can be used.High reliability and low latency are the main requirements.

NR sidelink (SL) unicast, groupcast, and broadcast design is described.SL broadcast, groupcast, and unicast transmissions are supported for thein-coverage, out-of-coverage and partial-coverage scenarios.

FIGS. 10 and 11 show an example of PC5 protocol stacks to whichimplementations of the present disclosure is applied.

FIG. 10 illustrates an example of a PC5 control plane (PC5-C) protocolstack between UEs. The AS protocol stack for the control plane in thePC5 interface consists of at least RRC, PDCP, RLC and MAC sublayers, andthe physical layer.

FIG. 11 illustrates an example of a PC5 user plane (PC5-U) protocolstack between UEs. The AS protocol stack for user plane in the PC5interface consists of at least PDCP, RLC and MAC sublayers, and thephysical layer.

For the purposes of physical layer analysis, it is assumed that higherlayers decide if unicast, groupcast, or broadcast transmission is to beused for a particular data transfer, and they correspondingly inform thephysical layer. When considering a unicast or groupcast transmission, itis assumed that the UE is able to establish which unicast or groupcastsession a transmission belongs to, and that the following identities isknown to the physical layer:

-   -   The layer-1 destination ID, conveyed via physical sidelink        control channel (PSCCH)    -   Additional layer-1 ID(s), conveyed via PSCCH, at least for the        purpose of identifying which transmissions can be combined in        reception when HARQ feedback is in use    -   HARQ process ID

For the purpose of Layer 2 analysis, it is assumed that upper layers(i.e., above AS) provide the information on whether it is a unicast,groupcast or broadcast transmission for a particular data transfer. Forthe unicast and groupcast transmission in SL, the following identitiesis known to Layer 2:

-   -   Unicast: destination ID, source ID    -   Groupcast: destination group ID, source ID

Discovery procedure and related messages for the unicast and groupcasttransmission are up to upper layers.

At least the following two SL resource allocation modes are defined asfollows.

(1) Mode 1: BS schedules SL resource(s) to be used by UE for SLtransmission(s).

(2) Mode 2: UE determines, i.e., BS does not schedule, SL transmissionresource(s) within SL resources configured by BS/network orpre-configured SL resources.

The definition of SL resource allocation Mode 2 covers:

a) UE autonomously selects SL resource for transmission

b) UE assists SL resource selection for other UE(s)

c) UE is configured with NR configured grant (Type-1 like) for SLtransmission

d) UE schedules SL transmissions of other UEs

For SL resource allocation Mode 2, sensing and resource(re-)selection-related procedures may be considered. The sensingprocedure considered is defined as decoding sidelink control information(SCI) from other UEs and/or SL measurements.

The resource (re-)selection procedure considered uses the results of thesensing procedure to determine resource(s) for SL transmission.

For Mode 2(a), SL sensing and resource selection procedures may beconsidered in the context of a semi-persistent scheme where resource(s)are selected for multiple transmissions of different TBs and a dynamicscheme where resource(s) are selected for each TB transmission.

The following techniques may be considered to identify occupied SLresources:

-   -   Decoding of SL control channel transmissions    -   SL measurements    -   Detection of SL transmissions

The following aspects may be considered for SL resource selection:

-   -   How a UE selects resource for PSCCH and physical sidelink shared        channel (PSSCH) transmission (and other SL physical        channel/signals that are defined)    -   Which information is used by UE for resource selection procedure

Mode 2(b) is a functionality that can be part of Mode 2(a), (c), (d)operation.

For out-of-coverage operation, Mode 2(c) assumes a (pre-)configurationof single or multiple SL transmission patterns, defined on each SLresource pool. For in-coverage operation, Mode 2(c) assumes that gNBconfiguration indicates single or multiple SL transmission patterns,defined on each SL resource pool. If there is a single patternconfigured to a transmitting UE, there is no sensing procedure executedby UE, while if multiple patterns are configured, there is a possibilityof a sensing procedure.

A pattern is defined by the size and position(s) of the resource in timeand frequency, and the number of resources.

For Mode 2(d), the procedures to become or serve as a scheduling UE forin-coverage and out-of-coverage scenarios may be considered as follows:

-   -   Scheduling UE is configured by gNB    -   Application layer or pre-configuration selects scheduling UE    -   Receiver UE schedules transmissions of the transmitter UE during        the session    -   Scheduling UE is decided by multiple UEs including the one that        is finally selected. The UE may autonomously decide to serve as        a scheduling UE/offer scheduling UE functions (i.e., by        self-nomination).

Until Rel-15, broadcast transmission is supported only for V2Xcommunication. Broadcast transmission means that V2X transmission by onewireless device is broadcast to several unspecified wireless devices. Incase of NR V2X, unicast and groupcast transmission may also be supportedfor V2X communication as well as broadcast transmission. Unicasttransmission means that V2X transmission by one wireless device istransmitted to one specified other wireless device. Groupcasttransmission means that V2X transmission by one wireless device istransmitted to several specified other wireless devices which belongs toa group. Unicast transmission is expected to be used for highreliability and low latency cases, e.g., extended sensor sharing andremote driving, emergency, etc.

In NR V2X, one wireless device may establish a PC5 link (e.g.,one-to-one connection and/or session between wireless devices) forunicast service with another wireless device. PC5 Signaling protocolabove RRC layer in the wireless devices may be used for unicast linkestablishment and management. Based on the unicast link establishmentand management, the wireless devices may exchange PC5 signaling (i.e.,upper layer signaling than RRC signaling) to successfully orunsuccessfully establish a unicast link with security activation orrelease the established unicast link.

FIG. 12 shows an example of PC5 link setup to which implementations ofthe present disclosure is applied.

Referring to FIG. 12, an initiating UE transmits a direct communicationrequest message to a target UE for PC5 link setup. Upon transmitting thedirect communication request message, the timer T4100 may start. Uponreceiving the direct communication request message from the initiatingUE, the target UE transmits a direct communication accept message to theinitiating UE in response to the direct communication request message.Upon transmitting the direct communication accept message, the timerT4108 may start. Upon receiving the direct communication accept messagefrom the target UE, PC5 link can be established successfully, upon whichthe timer T4100 may stop.

Alternatively, referring to FIG. 12, an initiating UE transmits a directcommunication request message to a target UE for PC5 link setup. Upontransmitting the direct communication request message, the timer T4100may start. Upon receiving the direct communication request message fromthe initiating UE, the target UE transmits a direct communication rejectmessage to the initiating UE in response to the direct communicationrequest message. Upon receiving the direct communication reject messagefrom the target UE, PC5 link setup procedure may stop, upon which thetimer T4100 may stop.

FIG. 13 shows an example of security mode control to whichimplementations of the present disclosure is applied.

Referring to FIG. 13, a commanding UE transmits a direct security modecommand message to a peer UE for security mode control. Upontransmitting the direct security mode command message, the timer T4111may start. Upon receiving the direct security mode command message fromthe commanding UE, the peer UE transmits a direct security mode completemessage to the commanding UE in response to the direct security modecommand message. Upon receiving the direct security mode completemessage from the peer UE, security mode can be controlled successfully,upon which the timer T4111 may stop.

Alternatively, referring to FIG. 13, a commanding UE transmits a directsecurity mode command message to a peer UE for security mode control.Upon transmitting the direct security mode command message, the timerT4111 may start. Upon receiving the direct security mode command messagefrom the commanding UE, the peer UE transmits a direct security modereject message to the commanding UE in response to the direct securitymode command message. Upon receiving the direct security mode rejectmessage from the peer UE, security mode control procedure may stop, uponwhich the timer T4111 may stop.

FIG. 14 shows an example of PC5 link release to which implementations ofthe present disclosure is applied.

Referring to FIG. 14, a releasing UE transmits a direct communicationrelease message to a peer UE for PC5 link release. Upon transmitting thedirect communication release message, the timer T4103 may start. Uponreceiving the direct communication release message from the releasingUE, the peer UE transmits a direct communication release accept messageto the releasing UE in response to the direct communication releasemessage. Upon receiving the direct communication release accept messagefrom the peer UE, PC5 link can be released successfully, upon which thetimer T4103 may stop.

However, exchange of PC5 signaling would be vulnerable to transmissionloss sometimes. Therefore, PC5 link setup and/or management may bedelayed or failed. Such delay and/or failure over PC5 signaling willresult service delay, interruption and/or blockage which could becritical to vehicles using road safety services. In other words, amethod for establishing and/or managing PC5 link with robustness may berequired.

FIG. 15 shows an example of a method for a first wireless deviceaccording to implementations of the present disclosure.

Referring to FIG. 15, the first wireless device may be in communicationwith at least one of a mobile device, a network, and/or autonomousvehicles other than the first wireless device. The first wireless devicemay be a wireless device initiating a signaling procedure (may be simplycalled an initiating wireless device). For example, the signalingprocedure may be connection establishment procedure. In this case, thefirst wireless device may be a connection requesting wireless device.

In step S1500, the first wireless device triggers a signaling procedurebased on a congestion level of at least one carrier.

In some implementations, the signaling procedure may include connectionestablishment. The signaling procedure may be mapped to the at least onecarrier.

In step S1510, the first wireless device selects a carrier among the atleast one carrier.

In some implementations, the selected carrier may have lower congestionlevel than a threshold. The threshold may be indicated by a network orother wireless device. In some implementations, the selected carrier hasa lowest congestion level among the at least one carrier. In someimplementations, the congestion level of the selected carrier and thecongestion level of other carriers among the at least one carrier arewithin a particular range.

In step S1520, the first wireless device transmits a message in thesignaling procedure on the selected carrier. The message includesinformation for the selected carrier.

In some implementations, when the signaling procedure corresponds toconnection establishment, the message may correspond to a connectionrequest message.

In some implementations, the selected carrier includes more than onecarrier. In this case, the message may be duplicated for the more thanone carrier, and the duplicated messages may be transmitted respectivelyon each of the more than one carrier.

In some implementations, the information for the selected carrier mayinclude the congestion level of the selected carrier. The message mayinclude information for carriers that the first wireless device supportsfor transmission and/or reception. The message may include an ID of thefirst wireless device and/or an ID of a second wireless device.

In some implementations, transmitting the message may compriseallocating a grant for the selected carrier, and transmitting themessage in the signaling procedure on the selected carrier by using thegrant. The grant may be created by the first wireless device and/orprovided by a network.

In some implementations, the message may be transmitted to a secondwireless device and/or a network.

In some implementations, the first wireless device may further monitor acarrier among the at least one carrier. In some implementations, thefirst wireless device further perform carrier reselection upon receivinga response message on the monitored carrier in response to the message.The reselected carrier may be one of the selected carrier.

In some implementations, when the signaling procedure corresponds toconnection establishment, the response message may correspond to aconnection response message.

In some implementations, the carrier reselection may be performed basedon information included in the response message. The information mayinclude the congestion level of the selected carrier. The informationmay include information for the selected carrier. The response messagemay include an ID of the first wireless device and/or an ID of a secondwireless device.

FIG. 16 shows an example of a method for a second wireless deviceaccording to implementations of the present disclosure.

Referring to FIG. 16, the second wireless device may be in communicationwith at least one of a mobile device, a network, and/or autonomousvehicles other than the second wireless device. The second wirelessdevice may be a target wireless device of a signaling procedure, e.g.,connection establishment procedure.

In step S1600, the second wireless device monitors at least one carrier.

In some implementations, the at least one carrier may be mapped to oneor more services. The one or more services may be related to unicasttransmission and/or groupcast transmission.

In step S1610, the second wireless device receive, from a first wirelessdevice, a first message on a first carrier among the at least onecarrier.

In some implementations, the first message may be related to a signalingprocedure.

The signaling procedure may include connection establishment. In someimplementations, when the signaling procedure corresponds to connectionestablishment, the first message may correspond to a connection requestmessage.

In some implementations, the first message may include information forthe first carrier. The information for the first carrier may include acongestion level of the first carrier. The first message may includeinformation for carriers that the first wireless device supports fortransmission and/or reception. The first message may include an ID ofthe first wireless device and/or an ID of the second wireless device.

In step S1620, the second wireless device performs carrier reselectionfrom the first carrier to a second carrier among the at least onecarrier.

In some implementations, the second carrier may be a carrier where thefirst message was received. In some implementations, the second carriermay be a carrier indicated by the first message.

In some implementations, the second carrier may have a congestion levellower than a threshold. The threshold may be indicated by one of thefirst wireless device, other wireless device or a network. In someimplementations, the second carrier may have a lowest congestion levelamong the at least one carrier. In some implementations, the secondcarrier may have a lowest congestion level among carriers indicated ormapped to the first message.

In step S1630, the second wireless device transmits, to the firstwireless device, a second message as a response to the first message.

In some implementations, when the signaling procedure corresponds toconnection establishment, the second message may correspond to aconnection response message.

In some implementations, the second carrier may include more than onecarrier, and the second message may be duplicated for the more than onecarrier. The duplicated second messages may be transmitted respectivelyon each of the more than one carrier.

In some implementations, transmitting the second message may compriseallocating a grant for the second carrier, and transmitting the messageon the second carrier by using the grant. The grant may be created bythe second wireless device and/or provided by a network.

In some implementations, the second message may include information forthe second carrier. The second message may include information forcarriers that the second wireless device supports for transmissionand/or reception. The second message may include an ID of the firstwireless device and/or an ID of the second wireless device.

FIG. 17 shows an example of for establishing a connection by aninitiating wireless device according to implementations of the presentdisclosure.

In step S1700, connection establishment is triggered. An initiatingwireless device (or, connection requesting wireless device) initiallyselects one or more carriers based on congestion level of carriers. Thecarriers may be mapped to what triggers the connection establishment.

In some implementations, the selected carrier may have a lowercongestion level than a threshold. In some implementations, the selectedcarrier may have the lowest congestion level among the carriers. In someimplementations, the initiating wireless device may select the othercarrier(s), so that the congestion level of the selected carrier and thecongestion level of the other carrier are within a particular range.

In step S1710, the initiating wireless device constructs a connectionrequest message for connection establishment. If the selected carrier ismore than one, the initiating wireless device may duplicate theconstructed connection request message.

In some implementations, the connection request message may includeinformation for the congestion level of the selected carrier. Theconnection request message may indicate one, some or all of the selectedcarrier. The connection request message may include information forcarriers that the initiating wireless device supports for transmissionand/or reception, e.g. for each band or each band combination. Theconnection request message may include a UE ID of the initiatingwireless device and/or a UE ID of other wireless device.

In step S1720, the initiating wireless device allocates a grant for eachselected carrier. The grant may be autonomously created by theinitiating wireless device or given by a network.

In step S1730, the initiating wireless device transmits the connectionrequest messages on the selected carrier to the other node by using theallocated grant. When the connection request message is duplicated formore than one selected carriers, the one message may be transmitted oneach of the more than one selected carriers.

In some implementations, the other node may be either other wirelessdevice, i.e., a target wireless device, or a network node such as a basestation.

In step S1740, the initiating wireless device monitors all carriersmapped to what triggers the connection establishment and/or all of theselected carrier.

In step S1750, the initiating wireless device receives a connectionresponse message on one of the monitored carrier from the other node inresponse to the connection request message. Upon receiving theconnection response message, the initiating wireless device re-selectsone or more carriers.

In some implementations, the re-selected carrier may be one of theinitially selected carriers.

In some implementations, the re-selected carrier may be reselected basedon information included in the connection response message. For example,the information may include congestion level information of theinitially selected carrier and/or an indicator for the initiallyselected carrier.

In some implementations, the connection response message may include theUE ID of the initiating wireless device and/or the UE ID of the othernode.

In step S1760, the initiating wireless device considers that theconnection with the other node is established. The initiating wirelessmay perform transmission on one or more of the reselected carriers tocommunicate with the other node. The initiating wireless may not use anycarrier which is initially selected but not reselected for transmission.

FIG. 18 shows an example of for establishing a connection by a targetwireless device according to implementations of the present disclosure.

In step S1800, the target wireless device monitors one or more carriers.

In some implementations, the one or more carriers may be mapped to oneor more services which the target wireless device may use. The servicemay be related to unicast transmission and/or groupcast transmission insidelink.

In step S1810, the target wireless device receives a connection requestmessage on one or more of the monitored carriers from an initiatingwireless device. Upon receiving the connection request message, thetarget wireless device constructs a connection response message inresponse to the connection request message.

In step S1820, upon receiving the connection request message and/orconstructing the connection response message, the target wireless device(re-)selects at least one carrier.

In some implementations, the selected carrier may be a carrier where theconnection request message was received. In some implementations, theselected carrier may be a carrier indicated by the connection requestmessage. In some implementations, the selected carrier may be a carrierwhich has a congestion level lower than a threshold. The threshold maybe indicated by the initiating wireless device or the other node such asa certain wireless device or a base station. In some implementations,the selected carrier may be a carrier which has the lowest congestionlevel among the carriers indicated by or mapped to the connectionrequest message.

In some implementations, if there are more than one selected carrier,the target wireless device may duplicate the connection responsemessage.

In step S1830, the target wireless device allocates a grant for eachselected carrier. The grant may be autonomously created by the targetwireless device or given by a base station.

In step S1840, the target wireless device transmits the connectionresponse message on the selected carrier to the initiating wirelessdevice by using the allocated grant. When the connection responsemessage is duplicated for more than one selected carriers, the onemessage may be transmitted on each of the more than one selectedcarriers.

In some implementations, the connection response message may includeinformation for the carrier where the connection response messages aretransmitted. The connection response message may include information forcarriers that the target wireless device supports for transmissionand/or reception. e.g., for each band or each band combination.

FIGS. 19 and 20 shows an example of PC5 connection establishment betweentwo UEs according to implementations of the present disclosure.

First, FIG. 19 is described.

In step S1900, UE1 (i.e., initiating UE in connection establishment) maycamp on a cell and may receive system information including at leastsidelink configuration via BCCH broadcast by gNB. The sidelinkconfiguration may include at least one or more resource pools which areused for several UEs to perform broadcast transmissions in sidelink.

In step S1902, UE2 (i.e., target UE in connection establishment) mayreceive dedicated signaling including at least sidelink configurationvia DCCH from gNB. The sidelink configuration may include at least oneor more resource pools which are used for several UEs to performbroadcast transmissions in sidelink.

In some implementations, based on mapping between carriers and ServiceA, UE1 may select one or more carriers where resource pools areconfigured for V2X sidelink communication and may allocate sidelinkgrant for sidelink broadcast services and/or monitor sidelinktransmissions on the selected carriers. UE1 may perform channel busyratio (CBR) on the resource pools and/or receive system informationindicating CBR level on the resource pools from gNB.

In step S1904, if connection establishment is triggered for a particularservice (e.g., Service A) for PC5, i.e., direct interface between twoUEs, UE1 may initially select one or more carriers based on CBR level ofthe carriers mapped to what triggers the connection establishment.

In some implementations, the number of the selected carriers may beconfigured by gNB or pre-configuration. In some implementations, theselected carrier may be mapped to what triggers the connectionestablishment (e.g., provider service identifier (PSID) and/or cause ofconnection establishment).

In some implementations, the selected carrier may have a lower CBR levelthan a threshold. In some implementations, the selected carrier may havethe lowest CBR level among carriers mapped to Service A. In someimplementations, UE1 may select the other carrier(s), so that the CBRlevel of the selected carrier and the CBR level of the other carrier arewithin a particular range.

In some implementations, the Service A may be defined by PSID. DifferentPSID values may be used to address different services for V2X sidelinkcommunication.

In step S1906, UE1 may allocate a grant for each selected carrier. Thegrant may be autonomously created by UE1 or given by a base station.

In step S1908, UE1 may transmit SCI to UE2. The SCI may indicatedestination of the sidelink transmission (e.g., UE2) and/or indicationto PC5 signaling.

In step S1910, UE1 may transmit a RRC PC5 connection request message onthe selected carrier to UE2 by using the allocated grant.

In some implementations, if the number of the selected carrier is morethan one, UE1 may construct the connection request message andduplicates the connection request message for the more than one selectedcarriers. The RRC layer, the PDCP layer and/or a lower layer may performduplication of the connection request message and/or a PDU/SDU carryingthe connection request message. In this case, each message of theduplicated connection request messages may be transmitted respectivelyon each carrier of the more than one selected carriers.

In some implementations, if UE1 establishes a PC5 connection for ServiceA, the connection request message may include direct communicationrequest for Service A provided by upper layers than RRC layer.

In some implementations, the connection request message may includeinformation for the congestion level (e.g., CBR level/value) of theselected carrier. The connection request message may include informationfor one, some or all of the selected carriers where the connectionrequest message is transmitted. The connection request message mayinclude information for carriers that UE1 supports for transmissionand/or reception. e.g., for each band or each band combination. Theconnection request message may include a UE ID of UE1 and/or a UE ID ofUE2.

In step S1912, UE2 may select one or more carriers mapped to one or moreservices including Service A. In step S1914, UE2 may monitor theselected carrier.

In some implementations, if UE2 receives the connection request messageon one or more of the monitored carrier from UE1, UE2 may construct aconnection response message in response to the connection requestmessage.

In some implementations, if UE1 requests establishment of a PC5connection for Service A, UE2 may determine whether to accept or rejectthe request. Based on this decision, the connection response message mayinclude direct communication accept or reject for Service A provided byupper layers than RRC layer.

In step S1916, upon receiving the connection request message and/orconstructing the connection response message, if the connection responsemessage becomes available in L2 buffer for a logical channel mapped tosidelink signaling (e.g., sidelink control channel (SCCH), UE2 selectsor reselects at least one carrier.

In some implementations, the selected carrier may be a carrier where theconnection request message was received. In some implementations, theselected carrier may be a carrier indicated by the connection requestmessage. In some implementations, the selected carrier may be a carrierwhich has a congestion level lower than a threshold. The threshold maybe indicated by UE1 or the other node such as a certain UE or a basestation. In some implementations, the selected carrier may be a carrierwhich has the lowest congestion level among the carriers indicated by ormapped to the connection request message.

Now, FIG. 20 which follows FIG. 19 is described.

In step S2000, if UE2 is in RRC_CONNECTED and configured for gNBscheduled sidelink resource allocation (i.e., Mode 1 described above),UE2 may transmit sidelink UE information to gNB. The sidelink UEinformation may include at least one of traffic pattern of Service A, TXcarriers and/or RX carriers mapped to Service A, QoS information relatedto Service A (e.g., 5G QoS indicator (5QI), proximity-based services(ProSe)-per-packet priority (PPPP), ProSe-per-packet reliability (PPPR),QoS class indicator (QCI) value), service type of Service A (e.g.,unicast transmission, groupcast transmission or broadcast transmission),and/or destination related to Service A and/or UE1 (e.g., destinationID, destination Index and/or UE ID mapped to Service A and/or UE1).

In step S2002, after receiving the sidelink UE information, gNB mayconstruct sidelink configuration at least including one or more resourcepools for Service A and/or unicast transmission with UE1 and Sidelinkbuffer status report (BSR) configuration such as mapping between alogical channel group (LCG) and one or more QoS values or mappingbetween a LCG and the service type of Service A. gNB may signal thesidelink configuration to UE2. Then, UE2 may configure lower layers withsidelink configuration.

In step S2004, if a message becomes available in L2 buffer for sidelinktransmission, UE2 may trigger scheduling request (SR) for sidelinksignaling (e.g., a particular SCCH and/or sidelink connectionestablishment), so that UE2 transmits PUCCH resource mapped to sidelinksignaling. If PUCCH resource is not configured, UE2 may perform randomaccess procedure as the scheduling request. If an uplink grant is givenat a result of the SR, UE2 may transmit sidelink BSR to gNB. Thesidelink BSR may indicate at least a destination index or UE Index, aLCG, and a buffer size corresponding to the destination service, thedestination group or the destination UE (UE1). The Destination Index mayaddress the destination service, the destination group and/or thedestination UE. The UE Index may address the destination/receiving UE,i.e., UE1.

In step S2006, after receiving the SL BSR, gNB may transmit a sidelinkgrant to UE2. e.g., by sending downlink control information (DCI) inPDCCH. The DCI may include an allocated sidelink resource, thedestination index and/or UE index. The index may be used to indicate theService A and/or UE1 explicitly or implicitly. If UE2 receives the DCI,UE2 may use the sidelink grant for transmission to UE1.

Alternatively, if UE2 is configured for UE autonomous scheduling ofsidelink resource allocation (i.e., Mode 2 described above), UE2 mayautonomously select and/or reselect sidelink resources to create asidelink grant used for transmission to UE 1.

In step S2008, UE2 may allocate a grant for each selected carrier. Thegrant may be autonomously created by UE2 or given by a base station.

In step S2010, UE2 may transmit SCI to UE1. The SCI may indicatedestination of the sidelink transmission (e.g., UE1) and/or indicationto PC5 signaling.

In step S2012, UE2 may transmit a RRC PC5 connection response message onthe selected carrier to UE1 by using the allocated grant.

In some implementations, if the number of the selected carrier is morethan one, UE2 may construct the connection response message andduplicates the connection response message for the more than oneselected carriers. The RRC layer, the PDCP layer and/or a lower layermay perform duplication of the connection response message and/or aPDU/SDU carrying the connection response message. In this case, eachmessage of the duplicated connection response messages may betransmitted respectively on each carrier of the more than one selectedcarriers.

In some implementations, the connection response message may includeinformation for the selected carrier where the connection responsemessage is transmitted. The connection response message may includeinformation for carriers that UE2 supports for transmission and/orreception, e.g., for each band or each band combination.

In step S2014, after transmission to UE2, UE1 may begin to monitor allcarriers mapped to Service A and/or what triggers the connection requestmessage and/or all of the selected carriers.

In step S2016, if UE1 receives the connection response message on one ofthe monitored carriers from UE2 in response to the connection requestmessage, the UE1 may re-select one or more carriers. That is, UE1 maytrigger the TX carrier reselection procedure.

In some implementations, the re-selected carrier may correspond to oneof the initially selected carriers. In some implementations, there-selected carrier may be reselected based on information included inthe received connection response message. For example, the informationmay include congestion level of the initially selected carrier and/or anindicator for the initially selected carrier or TX/RX carriers selectedby UE2 or UE capability of UE2.

In some implementations, the connection response message may include theUE ID of UE1 and/or the UE ID of UE2.

In some implementations, after receiving the connection responsemessage, UE1 may transmit acknowledgement to the connection responsemessage. The acknowledgement may be one of physical signaling and/orLayer 2 message such as a MAC control element (CE).

In some implementations, if the request was accepted, UE1 may considerthat the connection with UE2 is established, and then, may performtransmission on one or more of the reselected carriers to communicatewith UE2. UE1 may not use any carrier initially selected but notreselected for transmission.

In some implementations, if the request was accepted, UE1 maysuccessfully complete upper layer link establishment for Service A aswell as RRC connection establishment. In some implementations, if therequest was rejected, UE1 may unsuccessfully complete upper layer linkestablishment for Service A as well as RRC connection establishment.

In step S2018, after receiving the acknowledgement to the connectionresponse message from UE1, if the request was accepted, UE2 mayre-select one or more carriers. That is, UE2 may trigger the TX carrierreselection procedure. UE2 may consider that the connection with UE1 isestablished, and then, may perform transmission on one or more of thereselected carriers to communicate with UE1. UE2 may not use any carrierinitially selected but not reselected for transmission.

In some implementations, the re-selected carrier may correspond to oneof the initially selected carriers. In some implementations, there-selected carrier may be reselected based on information included inthe received connection request message.

The present disclosure can have various advantageous effects.

For example, one wireless device performing sidelink communication canperform fast and reliable connection establishment with another wirelessdevice by selecting multiple carriers of which congestion level is lowenough to provide sidelink grant and reliable signaling to the wirelessdevice with little loss, in particular when what triggers sidelinkconnection or sidelink service are mapped to multiple carriers.

For example, the system can provide fast and reliable sidelinkconnection establishment for a wireless device performing sidelinkcommunication with another wireless device.

Advantageous effects which can be obtained through specific embodimentsof the present disclosure are not limited to the advantageous effectslisted above. For example, there may be a variety of technical effectsthat a person having ordinary skill in the related art can understandand/or derive from the present disclosure. Accordingly, the specificeffects of the present disclosure are not limited to those explicitlydescribed herein, but may include various effects that may be understoodor derived from the technical features of the present disclosure.

Claims in the present disclosure can be combined in a various way. Forinstance, technical features in method claims of the present disclosurecan be combined to be implemented or performed in an apparatus, andtechnical features in apparatus claims can be combined to be implementedor performed in a method. Further, technical features in method claim(s)and apparatus claim(s) can be combined to be implemented or performed inan apparatus. Further, technical features in method claim(s) andapparatus claim(s) can be combined to be implemented or performed in amethod. Other implementations are within the scope of the followingclaims.

1. A method for a first wireless device in a wireless communicationsystem, the method comprising: triggering a signaling procedure based ona congestion level of at least one carrier; selecting a carrier amongthe at least one carrier; and transmitting a message in the signalingprocedure on the selected carrier, wherein the message includesinformation for the selected carrier.
 2. The method of claim 1, whereinthe signaling procedure includes connection establishment.
 3. The methodof claim 1, wherein the signaling procedure is mapped to the at leastone carrier.
 4. The method of claim 1, wherein the selected carrier haslower congestion level than a threshold.
 5. The method of claim 1,wherein the selected carrier has a lowest congestion level among the atleast one carrier.
 6. The method of claim 1, wherein the selectedcarrier includes more than one carrier, and wherein the message isduplicated for the more than one carrier.
 7. The method of claim 1,wherein the message is transmitted to a second wireless device and/or anetwork.
 8. The method of claim 1, further comprising monitoring acarrier among the at least one carrier.
 9. The method of claim 8,further comprising performing carrier reselection upon receiving aresponse message on the monitored carrier in response to the message.10. The method of claim 1, wherein the first wireless device is incommunication with at least one of a mobile device, a network, and/orautonomous vehicles other than the first wireless device.
 11. A methodfor a second wireless device in a wireless communication system, themethod comprising: monitoring at least one carrier; receiving, from afirst wireless device, a first message on a first carrier among the atleast one carrier; performing carrier reselection from the first carrierto a second carrier among the at least one carrier; and transmitting, tothe first wireless device, a second message as a response to the firstmessage.
 12. The method of claim 11, wherein the second carrier is acarrier where the first message was received.
 13. The method of claim11, wherein the second carrier is a carrier indicated by the firstmessage.
 14. The method of claim 11, wherein the second wireless deviceis in communication with at least one of a mobile device, a network,and/or autonomous vehicles other than the second wireless device.
 15. Afirst wireless device in a wireless communication system, comprising: atleast one transceiver; at least processor; and at least one computermemory operably connectable to the at least one processor and storinginstructions that, based on being executed by the at least oneprocessor, perform operations comprising: triggering a signalingprocedure based on a congestion level of at least one carrier; selectinga carrier among the at least one carrier; and transmitting a message inthe signaling procedure on the selected carrier, wherein the messageincludes information for the selected carrier.